Welcome back to the our channel for a discussion about the ways commercial and military aircraft are rigorously tested to ensure proper operation. Tailstrikes do not only occur in the VMU test. They can also occur in the TOP test (take-off performance test, which determines the basic data for calculating the take-off performance of an aircraft). For this reason, devices such as those shown in the video at 2:46 are installedat the tail so that the fuselage is not damaged too much. I think that with all my education and knowledge I've acquired over the years I think I could finally see myself working on this field, I'll be that dude always mixing the putty and filling up the holes in the models and parts all the time. Torture testing is always a good idea, to push your product beyond what it was designed to withstand until it fails under controlled conditions. With the rejected take off test the ARFF can approach the aircraft but can not apply any material for a period of time to account for real world response times. ARFF is usually on the airport grounds, especially for anywhere receiving a 747, but they are not usually sitting at the side of the runway unless an emergency is declared prior to arrival.